2020·全国·模拟预测
解题方法
1 . 根据《九章算术》商功中的描述,几何体“阳马”为底面为矩形,一条侧棱垂直于底面的四棱锥.现有阳马
,如图,
平面
,
,
,点
,
分别在
,
上,则当空间四边形
的周长最小时,直线
与平面
所成角的正切值为( )
![](https://img.xkw.com/dksih/QBM/2021/1/12/2634691823181824/2635328758038528/STEM/2d18465dba1a45eeb2196f65482c8f1e.png?resizew=174)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e7b6d04f024ca05cdfacc8ce9137c15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0d5a2cd05e4476fc72271e8fdb59a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed2455ff2c23cf7b59284eb68a9e5e80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0901e2f5cefe6468cbbcaa332287d63.png)
![](https://img.xkw.com/dksih/QBM/2021/1/12/2634691823181824/2635328758038528/STEM/2d18465dba1a45eeb2196f65482c8f1e.png?resizew=174)
A.![]() | B.![]() | C.![]() | D.![]() |
您最近一年使用:0次
名校
解题方法
2 . 在《九章算术》中,将四个面都为直角三角形的四面体称之为鳖臑.如图,在鳖臑
中,
平面
,
,且
,过点
分别作
于点
,
于点
,连结
,当
的面积最大值时,
( ).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/21/afa03cdd-5cd6-4624-9ddf-ead2147f4780.png?resizew=153)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9fd9540710e56838940d36d8a4802e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfbaf73297240eb116f22489519895a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f392902d611863c6908a48e696e7bd8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cc216d456790748fda154e2c73d0c4b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/21/afa03cdd-5cd6-4624-9ddf-ead2147f4780.png?resizew=153)
A.![]() | B.![]() | C.![]() | D.![]() |
您最近一年使用:0次